The invention is concerned with the type of spectacle case which is basically tubular in form, being closed at the bottom end, and having an open mouth at the top end. This type of open-mouth case may be contrasted with the type which comprises a box with a hinged lid.
In the type of spectacle case which comprises a box with a hinged lid, the case can be quite hard and rigid, and such a case offers excellent protection against the spectacles becoming scratched or otherwise damaged because, in this design, the spectacles are not gripped by the case in any way. On the other hand, when the case comprises a box with a hinged lid, it is not practically possible for a person to take the spectacles out of the case unless the person uses both hands.
The type of spectacle case with which the invention is concerned is the kind where the case has an open mouth at the top end, wherein it is possible for a person to insert and extract the spectacles with one hand.
In the conventional open-mouth design, the spectacles remain in the case primarily by the action of gravity. Thus, if the person leans forward, or indulges in vigorous movements, there is a danger that the spectacles might fall out of the case.
The conventional design of open-mouth case is such that whatever grip the case exerts on the spectacles is exerted by way of direct contact between the inside of the case and the glass of the spectacle lens. Because of this, if the contact is at all forceful, the lenses can, with use, and with repeated insertions and extractions of the spectacles, gradually become dulled or scratched.
With the conventional design of open-mouth case, experience has shown that if the case is tight enough upon the spectacles to provide a reasonably secure grip, then the case has to squeeze the spectacles so tightly to achieve the required grip that there is too high a chance that the spectacles may become damaged over time. An associated problem is that of course not all spectacles have the same dimensions, yet inevitably the strength of the case's grip depends on the dimensions of the spectacles.
The problem therefore may be summed up in that it has not proved possible, with the conventional design of open-mouth spectacle case, to provide sufficient grip to hold the spectacles in securely, and yet at the same time to permit the spectacles to be easily inserted into and removed from the case, with one hand, and without damaging the spectacles, over a useful range of sizes of spectacles.